This invention relates generally to a trenching apparatus which can be mounted on a conventional tractor.
Powered trenching devices are known. Typically, trenching machines include a boom having a continuous digging chain carried for sliding movement about the boom. Sprockets are provided on the boom for engagingly driving the digging chain in a circuitous path around the length of the boom. At least one of the sprockets is connected to the output of drive means, such as a motor or engine.
In use, the boom is forced downwardly into the ground while the digging chain is moving. The digging chain has teeth which break up and lift soil from below ground level above ground level, where the teeth deposit the soil on either side of the trench being dug. When the boom is forced downwardly such that the tip of the boom is at the desired depth of the trench, the trenching machine eases forward to provide a continuous trench at that depth.
Generally, a trenching device as described above is part of a dedicated trenching machine, such as those disclosed in U.S. Pat. No. 3,623,246, granted to Skomial, et al.; U.S. Pat. No. 3,209,473, granted to Davis; U.S. Pat. No. 3,206,876, granted to Penote, et al.; U.S. Pat. No. 3,050,881, granted to Brown; U.S. Pat. No. 2,981,012, granted to Meyer; and U.S. Pat. No. 2,935,801, granted to Stewart, et al. Dedicated trenching machines are by their very nature limited in versatility for uses other than trenching.
Where a trencher is needed on an occasional basis by, for example, a contractor or individual, for digging narrow trenches, a trencher which could be attached to a conventional tractor would be particularly desirable. Such trenchers would be particularly useful for digging trenches for laying cable and piping. However, such trenchers typically have relatively large power requirements, which limit the type of tractor on which they can be mounted, with a tractor having at least 40 horsepower generally being required.
U.S. Pat. No. 3,130,506, granted to Laster, discloses a trenching device which can be used on a tractor. U.S. Pat. No. 3,834,049, issued to Bond and German Patent No. 1,484,817 also disclose trenching devices for mounting on a tractor. Other tractor-mounted trenchers are manufactured by American Trencher, Inc., of Delhi, Iowa and by Burkeen, of Olive Branch, Miss.
A common problem with tractor mounted trenchers is that in order for the trencher to operate properly, the tractor must have a relatively large horsepower engine. Also, the tractor is sometimes required to have a hydrostatic drive or an exceptionally low drive gear, known as a "creeper" gear, which generally adds considerably to the cost of the tractor. Further, to increase the digging depth of the trencher, a costly extension is generally needed for the boom.